Tunnel Through The Cost Barrier To Net Zero

Because passive building principles tailor homes to their exact microclimate, they provide cost effectiveness, while simultaneously delivering a superior live/work environment

By KATRIN KLINGENBERG

As buildings get tighter, energy codes get steeper, and consumers expect more carbon-conscious options, builders face new challenges in meeting these elevated expectations.

Building professionals and consumers know about the disastrous effects of unintended consequences from early efforts at high-performance building. Exterior insulating systems got a bad rap in the Southeast, as did structural insulated panels in the Northwest. Add misguided and unintended vapor barriers throughout the humid South, and the mold outbreaks flourished, many insurance companies vanished, and builders got jumpy.

Decades of field data are available for building scientists to curate into hard won lessons of best practice guidelines and certification systems. These best practice packs can move you along the path of continual improvement—or energy code compliance, depending on how you look at it. Add inexpensive solar panels to the mix, and passive homes, which produce as much energy as they use, are affordably achievable almost anywhere.

Net zero is just a handful of steps away

With blower doors and continuous exterior insulation in the building code, it’s time for design and building professionals to bone up on tight construction methods and best practice passive principles. The 2015 International Energy Conservation Code (IECC) is an excellent place to begin because, well, it is the law. Even if your jurisdiction hasn’t adopted the 2015 code yet, it is wise to get up to speed with what is coming down the pike—blower doors, energy scores, and exterior insulation. Rather than moving the goalposts in the 2015 version, the ICC added flexibility to the code with a performance path, making it easier to hit the targets.

The Delphi Passive House provides a buffer for increasing sensitivity to light and thermal fluctuation coupled with decreased mobility. The house won first place in the 2017 Passive Building Design Awards.

Energy Star 3 and 3.1 is a significant next step that drives home the importance of air tightness, thermal bridges, and HVAC design to overall energy use. If you are aiming for net zero, then it is critical to understand how these work together. Before cheap solar, this is the low-hanging fruit. Energy Star certification is based on climate zones because each place faces different challenges and opportunities. Energy Star 3.1 can help building professionals make choices to deliver value and savings in light of the steeper 2012 IECC.

DOE’s Zero Energy Ready (ZER) Home program is field-tested by big builders like Mandalay Homes, Thrive Home Builders, and Palo Duro Homes, Inc., who have built more than 14,000 ZER homes since 2008. ZER homes exceed Energy Star and IECC requirements, while also hitting other health and efficiency targets like the EPA’s Indoor airPLUS certification, all EnergyStar appliances, and efficient duct and hot water distribution design.

Passive building is the total package

The pinnacle of high performance is passive building, and it is growing fast. The most common passive building certification in North America is PHIUS+, administered by the Passive House Institute US.

As systems and methods are refined, costs go down and adoption goes up. PHIUS+ is attractive to North American builders because it incorporates with existing standards and is cost optimized for specific climate zones.

PHIUS+ comes from the same building science that guided the IECC, Energy Star, and the ZER program. Where ZER homes tack on several discrete performance certifications, PHIUS+ designs begin with a cost- and climate-optimized package, placing quality assurance at the center. PHIUS+ projects are modeled using the WUFI Passive modeling software, and the models are remarkably accurate, as recently published data indicate.

Beyond energy performance, though, passive buildings are more comfortable, durable, healthy, predictable, and affordable. Since not all systems work the same everywhere, PHIUS+ leverages tradeoffs between climate zones to hit performance targets. Investments in windows, insulation, air tightness, heating, cooling, and ventilation are matched to the specific need to deliver the most bang for the buck in each particular climate zone. This can add up to attractive savings after just a few homes because the systems become apparent. In fact, one of the highest cost hurdles is just getting the design and building teams up to speed.

The value scales up nicely

Single-family homebuilders can find economies of scale as the team gains experience; but in multifamily, the savings can compound more quickly. A 58-bed long-term health facility in eastern Washington costs about $120,000 less to build than a comparable ‘built to code’ building. On the topic of payback, the architect remarked, Return on Investment’ presumes an initial investment. Because there was no additional investment beyond what was in the budget, the ROI is either spectacular or irrelevant—depending on how you think about it.”

When passive building principles are applied to buildings—houses, apartments, offices, and skyscrapers—you get predictable performance, unmatched comfort, superb air quality, and resiliency in the face of climate change and power outages.

Katrin Klingenberg is the Director of Passive House Institute US. She can be reached at www.phius.org or email info@passivehouse.us